In recent years, with the advent of information age, the speed and amount of information required for communication technology increase dramatically. Optical communication technologies add wings to the information age, but the information processing of nodes and routes still needs electronic circuits at present, which restricts the development of communication technologies in terms of speed, capacity and power consumption. Adopting photonic integrated circuits to replace or partially replace electronic integrated circuits for communication routes certainly will become the future direction of development. A photonic crystal (PhC) is a structure material in which dielectric materials are arranged periodically in space, and is usually an artificial crystal including of two or more materials having different dielectric constants. The electromagnetic modes in an absolute photonic band gap (PBG) cannot exist completely, so as an electronic energy band is overlapped with the absolute band gap of PhCs, spontaneous radiation is suppressed. The PhC having the absolute band gap can control spontaneous radiation, thereby changing the interaction between the fields and materials, and further improving the performance of optical devices.
Tunable photonic band gaps (PBGS) may be applied to information communication, display and storage. For modulating band gaps at high speeds by using external driving sources, many solutions have been proposed, e.g., controlling magnetic permeability by using a ferromagnetic material, and changing dielectric constant by using a ferroelectric material.
Most of the existing optical switches are realized by using a nonlinear effect, which requires the use of high-power light for control, thus it will inevitably consume a large amount of energy. In the presence of large-scale integrated system and a large number of communication users, the consumption of energy will become enormous. At the same time, the degree of polarization will affect signal-to-noise ratio and transmission speed.